rhizocarp
/ˈrʌɪzəʊkɑːp/Now rare
noun
Any plant of the (former) class Rhizocarpeae (now the family Marsileaceae) of aquatic and semiaquatic ferns; a marsileaceous plant.
Origin
Mid 19th century; earliest use found in John Balfour (1808–1884), botanist. From rhizo- + -carp, after either scientific Latin Rhizocarpae or German Rhizokarp.